May be it is usefull to add a part of the text of an old post of mine regarding the 12v battery during long time stand still:
.........to share our last experience with a long stand still during winter (every time about 2 and a half months). I have already shared the data of the battery-charge of our Jazz in the first 2 years. I can add the figures of this year. For clarity, I give the data of the 3 years together:
2022: departure 12,8V return: 11,9V
2023: departure 12,6 V return:11,6V
2024: departure 12,5V return: 11,7V
Even considering the soft Dutch winters (certainly in a garage), the small 12V battery is quite sturdy. The charge of the battery is deteriorating, but very slowly. And did I first wonder if the battery could cope with one long standstill of 2 and a half months (and was already searching for a fitting EFB-battery for replacement) now my only concern is that I can get exactly the same battery when I have to change the battery in a couple of years......
In two month time I could add the figures of 2025, but I will only mention it when the battery this time says that I have asked too much and that I have to use a charger or I have to replace it. So no news is good news